Another hint, try: out <- ode(state6, 0:100, BIOGEO6, parms=parameters6) init <- out[64, 2:29] outx <- ode(init, seq(63, 63.4, 0.01), BIOGEO6, parms=parameters6) tail(outx[,2:29]) ... that runs the model during the critical time period. You see that ZB, Q_N_Zost, Q_P_Zost and the nutrients crash first. Thomas